1. Field of the invention
The present invention relates to a method and an apparatus for reproducing acoustic information from a disk such as a CD (Compact Disk) recording acoustic information, the disk and cards used for the disk reproduction apparatus.
2. Description of Related Art
A disk reproduction apparatus has a CD mounted thereon and recording acoustic information as a digital signal, which digital signal is read out by a pickup while rotating the CD and an analog signal obtained by digital-to-analog conversion is amplified and outputted from the speaker. The CD has tracks recording acoustic information spirally formed on one of the surfaces thereof. There are 99 or less tracks, each of which is assigned a track number according to a predetermined standard. Each track is divided into 100 or less portions, each of which is assigned an index number also according to a predetermined standard. The index number, combined with the track number, constitutes an address. Each track is allotted with a read-in area recording TOC (Table Of Contents) information representing the address structure of the next program area or the like, a program area recording acoustic information and a read-out area recording ending information of all the programs sequentially from the leading portion of the track.
When the CD is mounted on and the reproduction start is commanded to the disk reproduction apparatus, the disk reproduction apparatus reads the TOC information from the CD and displays the information on the display for a predetermined length of time, after which the acoustic information recorded in the program area of the CD is reproduced sequentially from the leading portion. Upon application of the address mentioned above thereto, on the other hand, the disk reproduction apparatus reproduces the acoustic information recorded in the relevant address. Further, when a repeat command is given, the disk reproduction apparatus repeatedly reproduces the acoustic information or the designated address or a plurality of acoustic information between designated addresses.
In the conventional disk reproduction apparatus, when used for education, for example, the voice information recorded in the CD is reproduced and outputted so that a user can hear and learn the information. In this unidirectional type of operation, however, applications are limited only to narrow fields including the language education.
Also, there is a disk reproduction apparatus in which a CD recording a plurality of pieces of music is mounted, the digital signal read from the CD by a pickup arranged in opposed relation to the CD is converted into an analog signal and music is outputted from the speaker. In this type of apparatus, a desired piece of music is selected for reproduction from the CD by operating a music selection button on the body or ten-keys on a remote controller.
With the above-mentioned disk reproduction apparatus, it is difficult for infants to perform the music selection operation. U.S. Pat. No. 5,285,437 proposes the following disk reproduction apparatus. A card formed with a plurality of holes associated with the track numbers recording music is fitted in a card insertion slot of the body, and a plurality of optical sensors arranged in the card insertion slot detect the presence or absence and the position of a hole formed in the card, whereby the track number designated by the-relevant card is determined, the track number is accessed and the desired music is reproduced. In this disk reproduction apparatus, a picture and words of a song associated with the music designated by a card are printed on that card, so that infants can replace the card in the body and reproduce the desired music on the basis of the picture and the words printed on the card.
The conventional disk reproduction apparatus described above, when applied to the language education or the like, however, poses the following problem. Each area assigned a track number of the CD used for the language education is divided into a plurality of portions each assigned an index number. An address is constructed of a track number and an index number. The track number and the index number can use 0 to 99 according to a standard. As a result, a CD can have a maximum of 1.times.10.sup.4 addresses. Therefore, an index number can be assigned to each sentence, for example, recorded in a track, and only the sentence of a desired index number can be repeated and learned. In order to meet this requirement, however, a multiplicity of cards formed with holes for identifying addresses are required, which is not practical.
With CDs recording words, by contrast, they are classified into the beginners', middle and advanced courses, and the CD is appropriately replaced in accordance with the progress of the learning. Nevertheless, it is difficult for infants to replace the CD. Further, the CD is required for each of the beginners', middle and advanced courses, thereby leading to a high cost.